Laser Ultrasound and Optoacoustic Endoscopy of Esophagus We propose development of a novel commercial dual-modality imaging system which will integrate laser ultrasound and optoacoustic imaging capabilities in a compact package suitable for endoscopy of esophagus. There is a pressing need for versatile and effective instrumentation capable of detecting deadly esophageal cancer in its early stages. Ultrasound imaging has been proven effective in identifying and staging of relatively advanced tumors in esophageal wall lining based on differences in their density and speed of sound (acoustic impedance) relative to normal tissues. Optoacoustic imaging is a novel complementary imaging modality which combines optics and high-resolution of ultrasound to generate images based on optical properties of tissues. Enhanced performance of the dual-mode optoacoustic-ultrasound imaging as compared to conventional ultrasound was clinically demonstrated in detection and staging of breast cancers, and the optoacoustic imaging technology have been commercialized. We reasonably expect that the proposed device will significantly improve diagnostic capability of ultrasound endoscopy and therefore be highly desired in clinical practice. The proposed optoacoustic/ultrasound imaging system will utilize a number of innovations which will allow us to achieve top-notch performance and versatility. Our first key innovation involves the use an off-axis parabolic reflector in conjunction with a flat transducer array for optoacoustic endoscopy. The reflector, as we demonstrated, provides and ideal conversion of a spherical wavefront into a plane wave without losses or distortions. The use of a transducer array will allow us to expand limited depth of view of the focused system using dynamic ultrasound focusing and wavefront corrections. With an array, approximately 10-fold larger volume can be imaged in a single step as compared to diffraction-limited volume of a focused system. Finally, we propose to add ultrasound imaging capability to the optoacoustic endoscope using laser-generated ultrasound. A removable absorbing and acoustically transparent layer placed in the path of laser beam will generate strong and broadband pressure pulses propagating towards a sample and the reflected signals will be used to recreate an ultrasound image. This innovation will eliminate the need for pulse-receive switches known to generate electronic interference and will allow optimization of the transducer design for detection mode only, thereby simplifying and enhancing sensitivity of an imaging system. The PI is an internationally recognized leader in optoacoustic imaging technology and its commercialization and will guide the team of highly qualified experts in ultrasound imaging and optoacoustic tomography towards successful completion of a project. At present, no compact dual-mode optoacoustic-ultrasound imaging systems suitable for endoscopy applications have been either developed or commercialized. The proposed research will create a foundation towards development and future commercialization of a novel instrument. Our dual-modality optoacoustic-ultrasound imaging system is expected to have a high demand in clinic for functional endoscopy of esophagus. PUBLIC HEALTH RELEVANCE: Laser Ultrasound and Optoacoustic Endoscopy of Esophagus Efficient imaging technologies capable of early stage detection of deadly esophageal cancers are need in clinical practice. Here we proposed to enhance conventional ultrasound imaging used for detection and staging of tumors in esophageal lining by introducing a novel dual-mode optoacoustic-ultrasound imaging endoscopy system. The proposed design based on an off-axis parabolic reflector in conjunction with a transducer array will provide a significantly improved resolution, depth of focus, and the rate of data acquisition as compared to prior optoacoustic endoscopy designs. The use of laser-ultrasound to perform conventional ultrasound imaging will not complicate the probe design and will significantly expand its utility fr detecting and staging of esophageal cancers. The proposed dual-modality optoacoustic-ultrasound imaging system is expected to have a high demand in clinic for functional endoscopy of esophagus.